21400416 has 192 divisors, whose sum is σ = 69672960. Its totient is φ = 6359040.

The previous prime is 21400397. The next prime is 21400417. The reversal of 21400416 is 61400412.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21400417) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 455305 + ... + 455351.

It is an arithmetic number, because the mean of its divisors is an integer number (362880).

Almost surely, 2^21400416 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21400416, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34836480).

21400416 is an abundant number, since it is smaller than the sum of its proper divisors (48272544).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21400416 is a wasteful number, since it uses less digits than its factorization.

21400416 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 114 (or 100 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 21400416 is about 4626.0583653906. The cubic root of 21400416 is about 277.6349088363.

Adding to 21400416 its reverse (61400412), we get a palindrome (82800828).

The spelling of 21400416 in words is "twenty-one million, four hundred thousand, four hundred sixteen".